1. Field of the Invention
This invention relates to an image processing apparatus, an image processing method and a computer program product for judging whether image data include specific information related to copy protection.
2. Description of the Related Art
In connection with color copying machines, implementing an image recognition processing function to prevent counterfeiting of a copy-prohibited object, such as a banknote or valuable securities has been considered. One drawback of color copying machines is that they are expensive stand-alone devices. More recently, high quality copying has been attained using less expensive computers, computer peripheral apparatuses such as a color scanner and a color printer, and image processing software to edit an input and output image. A need has developed for using an image recognition processing function to prevent counterfeiting of a banknote and valuable securities for an inexpensive color image processing system using a color scanner and printer.
There are some known judging methods for judging whether an original is a copy-prohibited object or not. An original is judged based on a color spectrum distribution of image data (R,G,B data for each pixel) generated by scanning the original, and a comparison of the color spectrum distribution with copy-prohibited object data stored in a ROM, or based on a comparison of an image pattern of a part of the original(or the entire original) with a copy-prohibited object pattern stored in a ROM. The result of the judging is an evaluation value as to whether the original is a copy-prohibited object or not.
It is recently possible to make a copy-prohibited object by using a technology called digital watermark. The copy-prohibited object is altered to include information indicating whether the object is a copy-prohibited object. The process of making the copy-prohibited object is as follows. First, second digital information (sub-information) indicating that the object is copy-prohibited is attached to digital image data as the first digital information (main-information). Next, a printed document is made from the digital image data including the attached second information. Of course, the second digital information indicating that the object is copy-prohibited can be detected from the digital image data as a characteristic of the digital watermark. It is possible to detect the second digital information indicating that the object is copy-prohibited from newly-created image data which is created from the printed document by an image reading apparatus (e.g., a color scanner). This technology is called digital watermark and is increasingly used for prohibiting illegal copying of printed material.
In view of widespread use of computer peripherals to make color copies, a judging process chiefly made of software for a copy-prohibited object is preferable to a hardware one comprising many electrical circuits. Such a software process, however, uses too much processing power and takes too long to judge whether an image is of a copy-prohibited object or not and to process the image.